C# 使用LINQ的列表中的Groupby列表

我有两门课：

class Customer
{
    public string Name { get; set; }
    public string ZipCode { get; set; }
    public List<Order> OrderList { get; set; }
}

class Order
{
    public string OrderNumber { get; set; }
}

需要帮忙吗

var orders = br.CustOrderList
.Select(r => new
{
    r.ZipCode,
    r.Name,
    r.OrderList
})
.GroupBy(x => x.ZipCode); 

你只想按ZipCode分组，所以就按ZipCode分组

啊，是的，试试看

var order = br.CustOrderList
              .GroupBy(x = x.ZipCode);

---

无需从列表中选择新项目

这将满足您的需要：

var orders = br.CustOrderList
    .GroupBy(x => x.ZipCode)
    .Select(g => new
    {
        ZipCode = g.Key,
        Orders = g.SelectMany(x => x.OrderList)
    });

---

请你提供一下。您希望输入和预期输出的方式它只返回Zipcode。我还要那个Zipcode的订单列表

var orders = br.CustOrderList
    .GroupBy(x => x.ZipCode)
    .Select(g => new
    {
        ZipCode = g.Key,
        Orders = g.SelectMany(x => x.OrderList)
    });